Blind World


Corneal Replacement and Artificial Vision.
Scientists tout a new gel and experimental microchips as help for the vision impaired.





December 25, 2003.

BY KURT LOFT,
Media General News Service.




If you're among the over-40 crowd, come get your reward: failing eyesight.


Most people counter the inevitable with glasses or contacts. The less fortunate face surgery, or worse, suffer a disease that leads to partial or complete blindness. But scientists are offering light for the vision-challenged and hope to change the way people see the world around them.


Two promising approaches are a natural gel that corrects the age-related effects of presbyopia, or "old vision," and experimental microchips implanted in the retina. If refined and approved by the Food and Drug Administration, scientists say that both could greatly enhance options in eye care.


As people age, the lenses in their eyes harden, making it more difficult to focus on objects up close. Researchers at Washington University in St. Louis are working on a modified hydrogel to replace hardened lenses and those blurred by cataracts, one of the most common vision problems.


"If we can remove the lens and put in a material that is soft, like a young, healthy lens is at age 20, they would be able to focus on near and far objects," biomedical engineer Madalene Fetch says.


A number of companies are working on replacement lens materials, but Washington University scientists say theirs differs in one distinct way. The material is characterized by a reversible bond, meaning the gel can be liquefied, injected into the eye, then returned to a harder state like the original lens.


"The liquid takes the shape of the natural lens and forms a gel," researcher Nathan Ravi says. "It's transparent, soft, and can be made to match the optical, physical and mechanical properties of a young human lens."


In conventional cataract surgery, the doctor cuts the patient's eye, removes the old lens and inserts an intraocular lens. The new gel is designed to be injected into the eye as a liquid, where it molds itself in the empty lens capsular bag in the eye. The technique requires no incision or stitches and adapts naturally to the individual.


Another team of researchers has developed a tiny chip that fits into the retina, the wall along the back of the eye. Ten people have received the artificial silicon retina under FDA-approved safety tests, according to Optobionics Corp., an Illinois-based company that designed it. Officials hope that it will help people suffering from retinitis pigmentosa and age-related macular degeneration, two common, serious conditions that lead to blindness.


Retinitis pigmentosa includes a number of diseases affecting the photoreceptor layer or "light sensing" cells of the retina. Macular degeneration affects the macula, the center area of the retina, and leads to a loss of central vision.


"We found that in all the patients, there were moderate to substantial improvements in vision," says Alan Chow, a pediatric ophthalmologist who created the implant. "One woman had no light perception and now can see shapes in front of her."


The implant requires cutting a small hole in the retina, then inserting a microchip the size of a pinhead. Packed with 5,000 tiny light sensors, the chip converts light into electricity, which stimulates the surrounding retina. It contains microscopic solar sensors that allow it to operate without batteries or a wired attachment.



Kurt Loft is a staff writer for The Tampa Tribune in Florida.



2003, Media General, Inc. All Rights Reserved






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